1. Technical Field
The present invention relates to controlling a fan motor for driving a cooling fan mounted on a vehicle, and more particularly, to a control device and a control method that can control at the locking of a fan motor and control at the cancel of the locking of the fan motor.
2. Background Art
For example, an electric fan for a vehicle mounted on a vehicle having an AC (air-conditioner) built therein is used to cool a coolant flowing in an AC capacitor or a radiator by actuating two cooling fans. In such an electric fan for a vehicle, when a coolant temperature is higher than a predetermined temperature, the coolant temperature can be kept constant by turning on a relay to supply power to a fan motor for driving the cooling fan and controlling the ON/OFF of the relay.
In such an electric fan for a vehicle, for example, the cooling fan may be clogged with foreign particles and thus the fan motor may be locked. In this case, when the foreign particles are removed but the cooling fan is not driven as soon as the fan motor could be unlocked, the overheating may be caused for a short time.
As a structure for controlling the electric fan for a vehicle, JP-A-10-8959 suggests an electric fan device that includes a signal processing circuit for outputting a pulse signal for executing a PWM control process on the basis of a coolant temperature control signal from an engine control ECU, a driving circuit for amplifying the pulse signal to drive a MOS transistor for driving two electric motors in common, a smoothing circuit provided to prevent the occurrence of conductive noises at the time of switching the MOS transistor, an over-current protecting circuit restricting a motor current when any one electric motor is locked, a motor voltage detecting circuit for detecting a motor-applied voltage applied to the electric motors, and a transmitting circuit for supplying a clock signal to the signal processing circuit.
In JP-A-10-8959, since two electric motors are controlled in a PWM manner by the MOS transistor driving two electric motors in common, the structure of the electric fan device is simpler than a structure for individually controlling two electric motors.
In that when the locking of one of two electric motors is detected, the motor current is restricted by the over-current protecting circuit and the electric motor that is not locked is actuated to cool the engine, some cooling ability is secured.
Since the electric fan device includes a signal processing circuit outputting a pulse signal for executing a PWM control process on the basis of a coolant temperature control signal from an engine control ECU, a driving circuit amplifying the pulse signal to drive a MOS transistor for driving two electric motors in common, a smoothing circuit provided to prevent the occurrence of conductive noises at the time of switching the MOS transistor, an over-current protecting circuit restricting a motor current when any one electric motor is locked, a motor voltage detecting circuit detecting a motor-applied voltage applied to the electric motors, and a transmitting circuit supplying a clock signal to the signal processing circuit, there is a problem with an increase in size of the device.
In the electric fan device, when any one electric motor is locked, the electric motor not locked is actuated. Accordingly, there is also a problem that the unlocked electric motor could not return to a normal state as soon as the locked electric motor is unlocked.